/**
 * Created by JuntaoYi
 * Date 2020/3/30
 */
import React, { Component } from 'react';

class Clock extends Component {
    constructor(props) {
        super(props);
        this.state = {
            date: new Date()
        }
    }
    componentDidMount() {
        this.timerId = setInterval(() => {
            this.tick()
        },1000)
    }

    componentWillUnmount() {
        clearInterval(this.timerId);
    }

    tick() {
        this.setState({
            date : new Date()
        })
    }

    render() {
        return (
            <div>
                <h1>Hello world</h1>
                <h2>It is {this.state.date.toLocaleTimeString()}.</h2>
            </div>
        )
    }
}

export default Clock;
